EP2043211A2 - Laser device - Google Patents

Abstract

The device (1) has a collimator (7) for grouping input-output radiations (3) attached to each of single emitter laser diodes (2). The radiations of a single emitter laser diodes group (8) are combined together to radiation-array-groups (20, 23) by combined-tilted mirrors (10b-10d, 14, 18). Non-reflected input-output radiations are combined together with reflected input-output radiations from the mirrors. A part of the non-reflected input-output radiations and a part of the reflected input-output radiations are truncated at the mirrors, and do not contributed to the radiation-array-groups.

Description

The invention relates to a laser device having a plurality of single-emitter laser diodes whose individual output beams are superimposed to form a total output beam, according to the preamble of claim 1.

Such a laser device is known from the DE 20 2005 009 294 U1 , For the use of such a laser device for show laser projection purposes, it is of central importance that the best possible bundled overall output beam is present with the highest possible average power.

It is therefore an object of the present invention, a laser device of the type mentioned in such a way that at a given average power in the total output laser beam improved bundling of this output beam can be achieved.

This object is achieved by a laser device with the features specified in the characterizing part of claim 1.

According to the invention it was recognized that it is surprisingly quite possible to cut off a portion of the single output jets used on merge deflection elements, so that the cut-off part is not available as useful light. The apparent drawback that this truncation entails due to a reduction in total usable intensity is more than offset by the benefit of the possibility of tighter merging of the side-by-side single output jets. Overall, a well bundled overall output beam results, which can be used well for projection purposes.

It is also surprising that diffraction effects due to the cut-off individual beam components have no negative effect on a projection quality of the total output beam.

Cut-off intensities according to claim 2 represent a good compromise between the smallest possible portion of the intensity to be cut off and the closest possible merging of adjacently adjacent single output beams. However, more than 20% of the total intensity of a single output beam should not be cut off.

A laser device according to claim 3 ensures a total output beam, in which all individual output beams advantageously extend closely adjacent to one another.

An overall collimator according to claim 4 results in a further narrowing of the bundle diameter of the total output beam where the narrow bundle diameter is required in the projection. A typical 1 / e bundle cross section is a 1 / e bundle cross section averaged over all cross sectional directions of the bundle. An elliptical bundle propagating in the z direction, which has a 1 / e bundle cross section of 3 mm in the x direction and a 1 / e bundle cross section of 7 mm in the y direction, has a typical 1 / e bundle cross section of approximately 5 mm up. 1 / e bundle cross sections according to claim 4 have been found to produce a good projection quality as preferred.

Adjusted according to claim 5 deflection mirror cause a further narrowing of the total output beam. Here, the structure of the total output beam is used from a plurality of single output beams, wherein the single output jets can be adjusted independently in their direction. The energetic principal rays of the single output beams within the array beam array then collapse along the beam path of the array beam array as the spacing of adjacent energetic principal rays of the single output beams along the beam path decreases.

The development according to claim 6 makes use of the possibilities of independent adjustment of the single output jets in a particularly advantageous manner for generating a small cross section of the total output beam.

Specifications of the emissions of the single-emitter laser diodes according to claims 7 to 10 have been found to be particularly suitable for the use of such laser diodes in the laser device according to the invention.

Fig. 1

eine schematische Gesamtübersicht einer Laservorrichtung mit einer Mehrzahl von Singleemitter-Laserdioden, deren Einzel-Ausgabestrahlen zu einem Gesamt-Ausgabestrahl überlagert werden, wobei diese Laservorrichtung Teil einer schematisch dargestellten Gesamtvorrichtung zur scannenden Showlaser-Projektion ist;

Fig. 2

eine schematische Ansicht auf die Laservorrichtung gemäß der Schnittlinie II-II in Fig. 1;

Fig. 3

eine Ausschnittsvergrößerung gemäß dem Ausschnitt III in Fig. 1;

Fig. 4

eine Ausschnittsvergrößerung gemäß dem Ausschnitt IV in Fig. 2;

Fig. 5

ein Intensitätsprofil ausgewählter Einzel-Ausgabestrahlen gemäß den Schnittlinien V-V in den Fig. 3 und 4;

Fig. 6

schematisch die Emissionsfläche einer der Singleemitter-Laserdioden;

Fig. 7

einen Schnitt durch den Gesamt-Ausgabestrahl gemäß Linie VII-VII in Fig. 1, wobei lediglich die Einzel-Ausgabestrahlen der Singleemitter-Laserdioden dargestellt sind; und

Fig. 8 und 9

Schnitte durch den Gesamt-Ausgabestrahl gemäß Linie VIII-VIII in Fig. 1 in einer zu Fig. 7 ähnlichen Darstellung in verschiedenen Justagezuständen der Laservorrichtung.

An embodiment of the invention will be explained in more detail with reference to the drawing. In this show:

Fig. 1

a schematic overall view of a laser device having a plurality of single-emitter laser diodes whose single-output beams are superimposed to form a total output beam, said laser device is part of a schematically illustrated total device for scanning show laser projection;

Fig. 2

a schematic view of the laser device according to the section line II-II in Fig. 1 ;

Fig. 3

an enlarged detail according to the section III in Fig. 1 ;

Fig. 4

an enlarged detail according to the section IV in Fig. 2 ;

Fig. 5

an intensity profile of selected individual output beams according to the section lines VV in the 3 and 4 ;

Fig. 6

schematically the emission area of one of the single emitter laser diodes;

Fig. 7

a section through the total output beam according to line VII-VII in Fig. 1 wherein only the single output beams of the single emitter laser diodes are shown; and

8 and 9

Sections through the total output beam according to line VIII-VIII in Fig. 1 in one too Fig. 7 similar representation in different adjustment states of the laser device.

To illustrate positional relationships is the Fig. 1 and further figures associated with the drawing a Cartesian xyz coordinate system. The x-axis runs in the Fig. 1 up. The y-axis is perpendicular to the plane of the Fig. 1 towards the viewer and the z-axis runs to the right.

A laser device 1 has a plurality of single-emitter laser diodes 2 whose individual output beams 3 are superimposed to form a total output beam 4. The generated total output beam 4 is then used with the Light coupled further laser, so that a white light beam is generated, which is then scanned for show laser purposes, for example via a projection surface 5. The laser device 1 generates the red light portion of the white light beam to be scanned.

For example, laser diodes having an output wavelength of 660 nm and a mean output power of 130 mW in cw mode (continuous wave) are used as single-emitter laser diodes 2.

Fig. 6 6 shows a typical emission surface 6 of one of the single-emitter laser diodes 2. The emission surface 6 is approximately elliptical and has an extension of typically 1.5 μm in the x-direction and an extension of typically 1.0 μm in the y-direction. This expansion in the x- and y-direction in each case is associated with a typical beam divergence of the single output beam 3 of this single emitter laser diode 2. The smaller the transverse extent of the emission surface 6, the greater the single-emitter laser diode 2, the beam divergence in this transverse extent containing the main level. Each of the single emitter laser diodes 2 has immediately after the emission surface 6 a first collimator 7, which reduces the divergence of the single output beam 3 in the x-direction to about 7 mrad and in the y-direction to about 16 mrad. In the further course of the laser device 1 is due to these very small divergences in the x and y directions virtually no widening of the single output jets 3 available.

The long main axis of the emission surface 6, ie the x-axis, is no longer than 1.7 μm in the single-emitter laser diodes 2 used.

The aspect ratio of the divergences in the x and y directions is 1: 1.3 to 1: 2.5 for the single emitter laser diodes 2 used. This divergence ratio x / y is preferably 1: 1.5.

Other single emitter laser diodes may also be used, for example a single emitter laser diode with an output wavelength of 642 nm and a cw output power of 90 mW, a divergence in the x direction of 10 mrad and in the y direction of 21 mrad. Typical emission areas of the single emitter laser diodes used have extents of 1 μm in the y-direction and 1.5 to 5 μm in the x-direction.
Shown in the Fig. 1 a total of twelve of the single-emitter laser diodes 2, which are each arranged in three groups 8 to four of the single-emitter laser diodes 2. The four laser diodes 2 of a group 8 are each arranged on a common support and heat sink 9 in parallel and equidistant from each other, wherein they radiate in the positive z-direction. The laser diodes 2 in the Fig. 1 Group 8 shown on the left are labeled from bottom to top with 2a, 2b, 2c and 2d. Each of the laser diodes 2a to 2d is associated with a 90 ° deflecting mirror 10a to 10d. Selected these deflecting mirrors 10 serve to bring together the individual output beams 3 to the total output beam 4 and are therefore also referred to below as merging deflecting mirror. The merge serve the deflection mirror 10b to 10d.

The deflecting mirrors 10 are arranged not only offset relative to one another in the x-direction in accordance with the x-positions of the laser diodes 2 a to 2 d, but also offset relative to one another in the z-direction. This ensures that at each of the merging deflecting mirrors 10b to 10d, a first single output beam 3 not reflected by the merging deflecting mirror 10b to 10d has at least one second, from the merging deflecting mirror 10b to 10d reflected single output beam 3 is merged. This situation is exemplified by the merging deflecting mirror 10b in FIG Fig. 3 shown enlarged. The non-reflected by Zusammenführ-deflecting mirror 10b single output beam 3 is in the Fig. 3 with 3a and by the merging deflection mirror 10b by 90 ° reflected single output beam 3 is in Fig. 3 designated 3b.

Of the Fig. 3 It can be seen that the merging deflection mirror 10b is arranged such that neither the entire bundle cross section of the guided, non-reflected single output beam 3a nor the entire beam cross section of the reflected single output beam 3b is used contributing to a merged intermediate output beam 11. Rather, at the converging deflection mirror 10, a part of the non-reflected single output beam 3a and also a part of the reflected single output beam 3b are cut off, so that the cut-off cross-sectional parts do not contribute to the intermediate output beam 11. A boundary line between the used and the cut, each incident single output beam 3a, 3b and the cut portion of these individual output beams 3a, 3b is in the Fig. 3 shown at 12.

The intensity ratios between the used and the cut portions of the single output jets 3a, 3b illustrate Fig. 5 , The intensity profile of the single output beams 3 is approximately Gaussian in the single-emitter laser diodes 2. Beyond the boundary line 12, a maximum of 10% of the total bundle intensity is cut off. This means that 90% of the intensities of the individual output jets 3a and 3b are used in the intermediate output beam 11 after the merging deflection mirror 10b. The individual output beams 3a, 3b can thus be very narrow, with virtually no gap, with only slight losses, be led side by side. In the case of the merging deflecting mirrors 10c and 10d, the same conditions prevail with respect to the partial cutting off of the individual output beams 3 passed therethrough, as described above with reference to FIG Fig. 3 described at merging deflection mirror 10b. In the beam path of the single output jets 3, therefore, after the merging deflection mirror 10d, there is an intermediate output beam 11 with four individual output jets arranged next to each other without gap, wherein in each case 90% of the original beam emission of the laser diodes 2 is utilized.

This quadruple output beam is then deflected by another 90 ° deflecting mirror 13, so that it subsequently propagates in the positive z-direction. In the further course of this fourfold intermediate output beam 11 is guided past a further merging deflecting mirror 14. This passage is in a schematic overview in the Fig. 2 and enlarged in the Fig. 4 shown. At the merging deflection mirror 14, again about 10% of the intensity of the passing fourfold intermediate output beam 11 is cut off. The corresponding boundary line 12 is in the Fig. 4 located. At the same time, another fourfold intermediate output beam 15 is deflected by 90 ° in the xz plane by the merging deflection mirror 14, so that it then likewise propagates in the positive z direction. As the representation of Fig. 4 can be removed is, analogous to the merging deflecting mirrors 10b to 10d, not the entire intensity of the intermediate output beam 15 is reflected, but only 90% thereof. A truncated portion of the quadruple intermediate output beam 15, which is not reflected, is in FIG Fig. 4 shown in phantom at 16. The merging deflecting mirror 14 also ensures that in the beam path this merging deflecting mirror 14, the intermediate output beams 11, 15 closely adjacent to each other virtually without any gap, without losing more than 10% of the incident beam intensity. In each case, 10% of the incident intensity is also cut off from the intermediate output beams 11 and 15, so that with regard to the intensity used and the cut-off intensity, the conditions which have been mentioned above in connection with FIG Fig. 5 were explained.

After the merging deflection mirror 14, therefore, there is an intermediate output beam 17 which is composed of a total of eight individual output jets 3 in a 4x2 pattern, wherein four output jets 3 run next to one another in the x direction and two output jets 3 in the y direction one above the other ,

In the further course of the intermediate output beam 17, this passes through a further merging deflection mirror 18, the function of which corresponds to the merging deflection mirror 14. At merging deflection mirror 18, a further fourfold intermediate output beam 19 is coupled to the eightfold intermediate output beam 17 by 90 ° deflection, again 10% of the intensities of the reflected single output beams 3 and 10% of the intensities of the four directly on the convergence deflection mirror 8 passing single output jets 3 of the eight times intermediate output beam 17 are cut off.

After the merging deflecting mirror 18, there is thus an intermediate output beam 20, which is constructed of twelve individual output jets 3 running side by side with virtually no gap, with four individual output jets 3 next to one another in the x direction and three single output jets 3 in y Direction are arranged one above the other. This Twelve times the intermediate output beam 20, also referred to as a group beam array, is then narrowed by a group collimator to reduce the beam cross-section to a subsequent 1 / e beam cross-section, which is 4 to 5 mm in the illustrated embodiment. Since twelve times, ie 4x3, intermediate output beam 20 has an approximately square bundle cross section overall, the 1 / e bundle cross section indication represents the 1 / e diameter along the x or along the y direction.

The group collimator 21 is designed in the manner of a Galilean telescope with a plano-convex lens 21a and a plano-concave lens 21b. The narrowed group beam array 20 is then combined via a coupling-polarizer 22 with another narrowed group beam array 23, which was also formed in a corresponding manner from the outputs of twelve single-emitter laser diodes 2. The only difference between the group beam arrays 20 and 23 is that the group beam array 20 is linearly polarized in the x direction and the group beam array 23 is linearly polarized in the y direction.

After the coupling-in polarizer 22, the red total output beam 4 is present. In the further course, this is combined via a dichroic coupling-in mirror 24 with an overlay beam 25 comprising a green overall output beam 26 and a blue overall output beam 27. The dichroic Einkoppelspiegel 24 is maximum permeable to red light and maximum reflective of green and blue light. The overlay beam 25 is generated by superposing the green total output beam 26 and the blue overall output beam 27 on another dichroic launch mirror 28. The dichroic Einkoppelspiegel 28 is maximum permeable to green light and blue Light maximum reflective. The green total output beam 26 is generated, for example, by frequency doubling of a neodymium solid-state laser. The blue overall output beam 27 can also be generated by a neodymium solid-state laser, which is frequency-doubled in the resonator. The wavelength of the green total output beam is 532 nm. The wavelength of the blue total output beam is 473 nm.

After the dichroic coupling-in mirror 24, there is a white total output beam 29 which passes through a scanner 30. This scanner 30 deflects the total output beam 29 in a synchronized manner, so that a desired light pattern is produced on the projection surface 5, which is spaced apart from the scanner 30 by about 10 to 20 m. The operation of the scanner 30 is preferably synchronized with unillustrated intensity modulators located in the beam paths of the total output beams 4, 26 and 27 and independently modulating the three primary colors red, green and blue for imaging.

When all the single output jets 3 are exactly parallel to each other, the cross section of the total output beam 4 after the scanner 30 looks approximately as in FIG Fig. 7 shown. Due to the somewhat higher divergence in the y-direction, the single output jets 3 are widened somewhat more strongly in the y-direction than in the x-direction, so that the beam diameters Δy of the single output jets 3 are larger than the beam diameters Δx in x perpendicular thereto -Direction. This effect is compensated by the fact that in the y direction in the total output beam 4 there are three adjacent single output jets 3, while in the x direction four adjacent single output jets 3 are present be present, so that the total output beam 4 after the scanner 30 has an approximately square envelope.

Fig. 8 shows the total output beam 4 after further propagation by about 10 to 20 m shortly before hitting the projection surface 5. The representation after Fig. 8 is not to scale for illustration Fig. 7 , Due to the divergence, the individual output jets 3 are now widened more strongly, whereby adjacent single output jets 3 now penetrate.

Fig. 9 shows a situation in which the total output beam 4 was further merged by adjusting the single output beams 3 just before the projection surface 5. The deflecting mirrors 10 and in particular 14 and 18 were adjusted so that the single output jets 3 in the y-direction are all approximately at a height. From the three superimposed rows of fourfold intermediate output jets, a fourfold series of single output jets 3 has become, which strongly penetrate due to the long propagation path. Energetic main beams 31 of the individual output beams 3 are combined within the overall output beam 4, that is to say in particular within the group beam arrays 20, 23, along the beam path of these group beam arrays 20, 23 by this adjustment. By further adjustment of the deflection mirror 10, it is possible for the fourfold intermediate output beam after Fig. 9 to summarize even further in the x-direction. The bundle diameter of the total output beam is reduced in this way again, which improves the quality of the projection produced on the projection surface 5, in particular its contrast.

Claims (10)

Laser device (1) having a plurality of single-emitter laser diodes (2) whose individual output beams (3) are superimposed to form a total output beam (4), - wherein each single-emitter laser diode (2) is associated with a first collimator (7) for focusing each individual output beam (3), - wherein the individual output beams (3) of at least one group (8) of single emitter laser diodes (2) by means of a plurality of merging deflecting mirrors (10b to 10d, 14, 18) to at least one group beam array (20, 23) are merged, in which the individual output jets (3) run close to each other at least during a first common beam path, - Wherein at each merge deflection mirror (10b to 10d, 14, 18) at least a first, not reflected by the merge deflection mirror (10b to 10d, 14, 18) single output beam (3a) with at least a second, from the merge deflection mirror (10b to 10d, 14, 18) reflected single output beam (3b) is merged, characterized in that at least at individual merge deflection mirrors (10b to 10d, 14, 18) a portion of the non-reflected (3a) and / or a portion of the reflected (3b) single output beam (3) is cut off and not grouped Beam array (20, 23) contributes. Laser device according to claim 1, characterized in that the cut-off part (16) at least 5%, preferably at least 10% of the total intensity of the single output beam (3) before the merging deflection mirror (10b to 10d, 14, 18). Laser device according to claim 1 or 2, characterized in that at all merging deflecting mirrors (10b to 10d, 14, 18) a part of at least one of the single output beams (3) is cut off and not to the group beam array (20, 23 ) contributes. Laser apparatus according to one of Claims 1 to 3, characterized by an overall collimator (21) for reducing a bundle cross section of the at least one generated group beam array (20, 23), in particular to a typical 1 / e bundle cross section which is at most 10 mm, in particular at most 8 mm, more preferably at least 6 mm and even more preferably at most 5 mm. Laser device according to one of claims 1 to 4, characterized in that the merging deflecting mirrors (10b to 10d, 14, 18) and optionally further deflecting mirrors (10a, 13) are adjusted so that the energetic main beams of the single output beams (3) within the array beam array (20, 23) along the beam path of the array beam array (20, 23) together. Laser device according to claim 5, characterized in that the energetic main rays of the single output beams (3) after an optical path of the group beam array (20, 23) of more than 1 m, preferably more than 5 m, even more preferred more than 10 meters, more preferably 20 meters. Laser device according to one of Claims 1 to 6, characterized by the use of single-emitter laser diodes (2) with an aspect ratio (y / x) of an emission surface (6) which lies between 1: 1 1 and 1: 5, in particular with an aspect ratio (y / x) in the range between 1: 1.3 and 1: 1.7. Laser device according to claim 7, characterized in that a long major axis (x) of the emission surface (6) is not longer than 2 μm, in particular not longer than 1.7 μm. Laser device according to claim 7 or 8, characterized by the use of single emitter laser diodes (2) with an aspect ratio of a divergence (x / y) of the single output beam (3), which lies between 1: 1 and 1: 2, in particular with a Aspect ratio (x / y) in the range of 1: 1.3 and 1: 1.7. Laser device according to one of claims 7 to 9, characterized in that the maximum beam divergence of the single-emitter laser diodes (2) is not greater than 30 mrad, in particular not greater than 20 mrad.

Images